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981.
基于不同植被类型,探讨辽河三角洲土壤的水盐状况,研究土壤全盐与土壤含水量及土壤pH值之间的关系。结果表明:辽河三角洲植被类型不同,土壤盐分、土壤含水量及土壤pH值明显不同。不同土层裸滩土壤全盐量均较高,小叶杨最低。翅碱蓬、紫花苜蓿、芦苇和柽柳作为盐生植被,对土壤含盐量影响较大。不同土层小叶杨土壤含水量均较低。裸滩、翅碱蓬及芦苇受潮汐影响较大,土壤含水量差异较大。调查区土壤pH值偏碱性,变化范围为7.30—8.97。土壤全盐、土壤含水量及土壤pH值之间总体呈显著相关,可见土壤含水量和pH值是显著影响土壤全盐量的重要因素。 相似文献
982.
Chenxi Wu Alison L. Spongberg Jason D. Witter Min Fang April Ames Kevin P. Czajkowski 《洁净——土壤、空气、水》2010,38(3):230-237
Increasing research has suggested that biosolids generated from municipal wastewater treatment can be a major sink for many pharmaceuticals and personal care products (PPCPs) and their land application potentially introduces these contaminants into the terrestrial and aquatic environments. In this study, methods were developed for the analysis of 14 PPCPs in biosolids and soils using pressurized liquid extraction, solid phase extraction and liquid chromatography‐tandem mass spectrometry. Recoveries were over 50% for all analytes except diphenhydramine (?30%) in soils. Soil properties or type of biosolids showed minor effects on method recoveries. Estimated method limits of quantification (LOQ) range from 0.1–15 ng g–1 for soil and 0.3–27 ng g–1 for biosolids. A field study utilizing the methods revealed that other than carbamazepine‐10,11‐epoxide, all targeted compounds were detected in biosolids. Diphenhydramine, fluoxetine, triclosan and triclocarban were detected up to the μg g–1 range with the highest concentration of 23 μg g–1 for triclocarban. Seven of the PCCPs found in biosolids were also detected in agricultural soils amended with these biosolids and several (carbamazepine, diphenhydramine, and triclocarban) appeared to be persistent in soils. Triclocarban was also found most abundant in soils with the highest average concentration of 0.2 μg g–1 while the rest of compounds were in the lower ng g–1 range. Generally, the concentrations found on the fields were 2–3 degrees of magnitude lower than in the biosolids, which is likely to be due to dilution, degradation and leaching processes. 相似文献
983.
A case study of long-term field performance of check-dams in mitigation of soil erosion in Jiangjia stream,China 总被引:3,自引:0,他引:3
This paper examines the long-term field performance of the check-dams in mitigation of soil erosion in the Duozhao catchment
of Jiangjia stream, southwest China. Since their construction between 1979 and 1982, the check-dams have been functioning
effectively. The examination is made via comparisons between the environmental conditions of the Duozhao catchment with its
adjacent Menqian catchment in the stream, because no check dams were constructed in the Menqian catchment. The examination
is based on recent field investigations and aerial photograph analyses, and covers four aspects: (a) bed gradients of catchment
channels; (b) stability of bank slopes; (c) rates of land erosion; and (d) vegetations on bank slopes. The field data demonstrate
that the check-dams have had the following good functions for mitigation of soil erosion: (1) restricting the channel depth
and lateral erosions, (2) protecting the channel erosion base, (3) reducing the bed gradients of debris-flow channels, (4)
fixing the channel bed, (5) stabilizing the bank slopes, as well as (6) facilitating the growth of vegetations.
Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users. 相似文献
984.
Using soil and contaminant properties to assess the potential for groundwater contamination to the lower Great Lakes,USA 总被引:1,自引:0,他引:1
Contaminant risk factors in surface soil were evaluated within the urbanized Rouge River watershed in southeastern Michigan,
USA, which includes metropolitan Detroit. An analytical risk factor model and Geographic Information Systems overlays were
used to quantify and characterize the potential impacts of five categories of contaminants including DNAPLs (dense nonaqueous
phase liquids), LNAPLs (light nonaqueous phase liquids), PAHs (polynuclear aromatic hydrocarbons), PCBs (polychlorinated biphenyls),
and lead. The results indicate that DNAPL compounds released into sand, moraine, and sandy and silty clay soil types have
the greatest potential to affect groundwater, and impact the Great Lakes ecosystem and the public health. 相似文献
985.
Yongcun Zhao Xianghua Xu Jeremy Landon Darilek Biao Huang Weixia Sun Xuezheng Shi 《Environmental Geology》2009,57(5):1089-1102
Topsoil samples (0–20 cm) (n = 237) were collected from Rugao County, China. Geostatistical variogram analysis, sequential Gaussian simulation (SGS),
and principal component (PC) analysis were applied to assess spatial variability of soil nutrients, identify the possible
areas of nutrient deficiency, and explore spatial scale of variability of soil nutrients in the county. High variability of
soil nutrient such as soil organic matter (SOM), total nitrogen (TN), available P, K, Fe, Mn, Cu, Zn, and B concentrations
were observed. Soil nutrient properties displayed significant differences in their spatial structures, with available Cu having
strong spatial dependence, SOM and available P having weak spatial dependence, and other nutrient properties having moderate
spatial dependence. The soil nutrient deficiency, defined here as measured nutrient concentrations which do not meet the advisory
threshold values specific to the county for dominant crops, namely rice, wheat, and rape seeds, was observed in available
K and Zn, and the deficient areas covered 38 and 11%, respectively. The first three PCs of the nine soil nutrient properties
explained 62.40% of the total variance. TN and SOM with higher loadings on PC1 are closely related to soil texture derived
from different parent materials. The PC2 combined intermediate response variables such as available Zn and P that are likely
to be controlled by land use and soil pH. Available B has the highest loading on PC3 and its variability of concentrations
may be primarily ascribed to localized anthropogenic influence. The amelioration of soil physical properties (i.e. soil texture)
and soil pH may improve the availability of soil nutrients and the sustainability of the agricultural system of Rugao County. 相似文献
986.
Using field surveys and laboratory analysis, soil physical and chemical properties were studied at a site exhibiting the reversal
of desertification in Yanchi County of China’s Ningxia Hui autonomous region. The dominant soil particle size changed from
coarse-fine sand to a combination of very fine sand and silt + clay, and corresponding levels of each soil nutrient increased.
The content of coarse-fine sand (2–0.1 mm) was significantly and negatively correlated with soil nutrient contents, whereas
nutrient contents were significantly and positively correlated with the contents of very fine sand (0.1–0.05 mm) and silt + clay
(<0.05 mm). The increasingly fine soil texture and the nutrient enrichment both facilitated rehabilitation of desertified
land. The silt + clay content contributed the most to the increasing soil nutrient contents, and thus appears to be the key
factor in reversal of desertification. Soil nutrient concentrations in the bulk soil increased with increasing content of
soil nutrients with different particle fractions, and there were significant positive correlations between them. The nutrients
in all particle size classes jointly decided the effect of soil nutrient contents on the reversal process. Principal-components
analysis (PCA) revealed that the soil quality tended to increase during the reversal process, and that nutrient factors were
more significant than particle size (i.e., were the dominant factor that influenced soil quality). Available nutrients and
soil organic matter (SOM) were the most important nutrient factors. Silt + clay were the most important particle factors. 相似文献
987.
Measurements taken between July 2006 to May 2007 at the Maqu station in the Upper Yellow River area were used to study the
surface radiation budget and soil water and heat content in this area. These data revealed distinct seasonal variations in
downward shortwave radiation, downward longwave radiation, upward longwave radiation and net radiation, with larger values
in the summer than in winter because of solar altitudinal angle. The upward shortwave radiation factor is not obvious because
of albedo (or snow). Surface albedo in the summer was lower than in the winter and was directly associated with soil moisture
and solar altitudinal angle. The annual averaged albedo was 0.26. Soil heat flux, soil temperature and soil water content
changed substantially with time and depth. The soil temperature gradient was positive from August to February and was related
to the surface net radiation and the heat condition of the soil itself. There was a negative correlation between soil temperature
gradient and net radiation, and the correlation coefficient achieved a significance level of 0.01. Because of frozen state
of the soil, the maximum soil thermal conductivity value was 1.21 W m−1°C−1 in January 2007. In May 2007, soil thermal conductivity was 0.23 W m−1°C−1, which is the lowest value measured in the study, likely due to the fact that the soil was drier then than in other months.
The soil thermal conductivity values for the four seasons were 0.27, 0.38, 0.55 and 0.83 W m−1°C−1, respectively. 相似文献
988.
大型天然黄土洞穴系统现场冲刷试验 总被引:1,自引:0,他引:1
摘 要:通过现场冲刷试验,结合勘探、调查及室内含泥率测定等手段对大型天然黄土洞穴系统的三维空间展布特征、水文特性及侵蚀特征进行了研究。结果表明:黄土洞穴系统侵蚀过程具有明显的期次性;洞穴过水流量过程曲线可分为增加阶段、相对稳定阶段和减小阶段三个特征流量段,其中在第一阶段普遍存在滞流效应,第二阶段具有小幅波动的特性,并发现洞穴内的总渗流损失量随设计注水流量的增大而有所增加;根据含泥率随时间变化曲线,分析了不同流量过程段含泥率的变化特点,通过不同工况的累积侵蚀量对比发现洞穴的侵蚀速率与流量显著正相关。从机理上对产生上述过程、现象及结果的原因进行了合理解释,为黄土潜蚀机理及潜蚀速率的研究提供了可靠的现场试验数据。 相似文献
989.
990.
XiaoguangZHAO HuiSHI Ming'anSHAO 《国际泥沙研究》2004,19(3):202-209
he slopes in field conditions are always irregular, but the supposed uniform slopes are used in most erosion models. Some studies used several uniform slopes to approximate an irregular slope for estimating soil erosion. This approximation is both time-consuming and weak in physical insights. In this paper, the concept of equivalent slope is presented based on that runoff potential on uniform slope is equal to that of irregular slope, and the equivalent uniform slope is used to estimate soil erosion instead of the irregular slopes. The estimated results of slope-length factors for convex and concave slopes are consistent with those from the method of Foster and Wischmeier, The experiments in the southern part of the Loess Plateau in China confirmed the applicability of the present method. The method is simple and has, to some extent, clear physical meanings, and is applicable for estimating soil erosion from irregular slopes. 相似文献